Update: Coinbase now provides a verification process for getting BTC within seconds rather than 4 days. Seems really good but I don't have the appropriate credit card. 
Other options are localbitcoins.com, cashintocoins.com, and bitcoinget.com.
Other options are localbitcoins.com, cashintocoins.com, and bitcoinget.com.
Coinbase's "instant buy" is limited to only 0.10 BTC per day. What a joke!
Otherwise, you are subject to their whims and have to wait 4-5 days for your order to go through at an arbitrary price (usually ends up a higher rather than lower price)!